[Elecraft] Electrolytic Capacitor failure

[Gill]

Hi David,
I was a civilian Electrical Engineer with the US Army before the FAA 
stint. We absolutely required the components used in critical systems to 
be operated well below the "rated" thresholds. I did HV substation 
design for places such as Marshall Space Flight Center and Redstone 
Arsenal - the Army missle development center where the original Redstone 
rocket was developed to launch the USA's 1st satellite in 1958. I was 
bombarded by manufacturers wanting us to use the 'latest' electronic 
versions of the substation protective relaying systems in the 1990's 
which until then had been totally analog. I refused to allow that then, 
primarily because they relied on electrolytic capacitors in their 'power 
supply' & 'transient bypass' systems (internally to the relay). The 
electrolytic caps were the weak link. A 161Kv substation is no place for 
components sensitive to transients & guaranteed to fail after 10 yrs or 
so. Those same caps have destroyed more PC motherboards, HD TV sets, 
etc. than any other cause. I have a ESR meter which allows one to check 
PC board caps in circuit - It uses an AC low level voltage which will 
not cause semiconductors to activate, & which gives ESR values for the 
caps. We used to try to repair expensive PC boards in the FAA systems 
rather that "board changing". That way we could keep one good spare & 
fix the failed one when replaced, keeping it as the spare. Electrolytic 
Cap's were the main culprits in the failures.
Thanks for the reply!
73 Gill